If there is a default, it could hurt in direct ways, by stopping payments for cash grants and loan guarantees that support many renewables projects. It could also hit innovation, by putting the Department of Energy program for cutting-edge energy technologies, ARPA-E, at risk.

A default could also hit indirectly, by pushing down the value of the U.S. dollar, as well as pushing up interest rates, which would affect financing for renewables projects that require large up-front investment.

The tariff on imported ethanol is likely to go soon as well, reported Ethanol Producer—either at the end of the year when current legislation expires, or sooner, if that legislation is repealed by a deal on the debt ceiling.

The oil the U.S. buys would go further under new auto efficiency standards Obama is expected to announce on Friday, which would require cars by 2025 to average 54.5 miles per gallon, compared with current requirements of 30.2 mpg.

But Germany is looking to catch up. Both houses of Parliament have now passed a new energy bill, which has more aggressive targets for expanding renewable energy, and includes higher tariffs for biomass, geothermal energy and offshore wind. But according to an analysis by Rhenish-Westphalian Institute for Economic Research, the transition to renewable energy is likely to be more expensive than the government has said.

A Warm Cloud

Server farms—which store and process huge amounts of data that zing around via the internet—eat up a lot of electricity, but the heat they spit out could be put to use, argued scientists at Microsoft Research and the University of Virginia. They propose putting servers in buildings, where the waste heat could heat the buildings, to save ­on energy—and it could also create faster, more secure networks.